Marine water tube boiler



3 H. TREDE MARINE WATER TUBE BOILER Filed Nov. 16, 1936 Patented Mar. 7, 1939 PATENT OFFICE MARIN E. WATER TUBE. BOILER Hans T'rede, Kassel-Wilhelmshohe, Germany, as-

signor to the firm of Schmidtsche Heissdampf Gesellschaft, m. b. H., Kassel-Wilhelmshohe,

Germany Application November 16, 1936, Serial No. 111,147 In Germany December 4, 1935 11 Claims. (01. 122-236 The invention relates to marine water tube boilers with upper and lower drums or headers and a combustion chamber which is disposed between the vaporizer tubes connecting the drums and from which the combustion gases are passed off at the bottom.

It is an object of the invention to provide an arrangement of tubes in a marine boiler so as to obtain a more eflicient heating thereof.

The invention resides in the fact that heating flues are provided at one or both sides of the combustion chamber by walls formed of the vaporizing tubes in which heating flues the heating gases from the combustion chamber ascend behind a tube wall which encompasses said chamber, said wall being heated on one side by the fire in the chamber and on the other side by the gases in the flue. The heating gases coming from the combustion chamber pass into the heating flue at a very high temperature, and, if necessary, subsequent combustion may take place in the heating flue. vaporizing tubes placed adjacent the rear of the boiler are also heated by the gases which ascend behind the inner tube wall. The vaporizing heated surfaces thus consist of intensely heated tubes, which are especially highly heated in their lower part. As a result very great vaporizing efiiciency can be attained with relatively small heating surfaces. This is particularly advantageous for marine boilers by reason of the economy of space and Weight obtained.

As the vaporizer tubes are more highly heated in the lower than in the upper part the water circulation is promoted and maintained during sea travel because the water, notwithstanding any retardations arising from the movement of the ship, is nevertheless carried upwardly by the steam bubbles forming in the lower part of the tube. The upper parts of the tubes are thereby Well cooled from the interior, so that unpermissibly high tube wall temperatures do not arise, as the ascending combustion gases are relatively cooled when they pass over these parts of the tubes.

Two embodiments of the new boiler are illustrated in the drawing, in which:

Fig. 1 is a. view showing a vertical cross section through the boiler, and

Fig, 2 is a similar view of a the invention.

As shown, the boiler A has upper and lower headers connected by tubes, and a smoke stack.

In the embodiment of Fig, 1 the upper header I and the lower header 2 are connected by two modified form of tube groups which encompass the combustion chamber 3, which is of generally rectangular cross section. The tubes 4, 5, positioned next to the combustion chamber, of the two lateral tube groups, form closed tubular walls which are the walls and ceiling of the combustion chamber. On the other hand, the tubes are spaced apart at the bottom of the combustion chamber at 4 5 so as to provide passages for the combustion gases therebetween. The outer tube series 6, l of the two tube groups form compact tubular walls at the bottom and at the lateral walls of the combustion chamber. At the top of the combustion chamber the tubes 1 of the right group are spaced apart at 1 so as to provide passages for the exit of the heating gases. In this manner two heating flues 8, 9' are formed in the two tube groups, which ascend behind the lateral walls of the combustion chamber formed by the tubes 4 and 5 and terminate above in the smoke stack It], in which heating surfaces, as, for example, a superheater l2 and a feed water pre-heater l3 and, if necessary, also an air preheater can be disposed.

Descending tubes or downcomers M, which are distributed over the entire length of the boiler, are disposed behind the outer tubular wall of the left tube groups formed by the tubes 6.

Subsequent combustion can take place in the heating flues, in which great smoke gas velocities arise. If necessary, air can be passed for this purpose into these heating flues as at 3| by special regulatable devices.

The number of vaporizing tubes may be varied as desired, and additional tubes may be placed in the flue. In the embodiment shown vaporizer tubes l5 are arranged in the left heating flue and vaporizer tubes IS in the right. The vaporizer tubes I B are contracted over a portion of their length into a tubular wall l'l, so that a portion of the heating gases ascending in flue 9 do not pass directly to the smoke collector, but must flow along on the cover of the combustion chamber to the opposite side.

The burners l8, which may be oil burners, for heating the combustion chamber, project the flame in the direction of the longitudinal axis of the boiler, and are disposed in the upper part of the combustion chamber. The combustion gases are forced to pass 01? through the passages provided at the bottom of the combustion chamber between the tube rows spaced at 4 and 5 'The gases then rise behind the inner tubular side walls 4, 5 and pass over the ceiling of the combustion chamber to the smoke outlet. this manner the vaporizer tubes are heated to the 

